Greenland ice sheet melting can cool subtropics, alter climate

A new study finds evidence that the last time Earth was as warm as it is today, cold freshwater from a melting Greenland ice sheet circulated in the Atlantic Ocean as far south as Bermuda, elevating sea levels and altering the ocean's climate and ecosystems.

The research shows a large pulse of cold freshwater covered the North Atlantic for a brief period of time about 125,000 years ago. The freshwater likely came from meltwater from the Greenland ice sheet and severely disrupted Atlantic Ocean circulation, likely killing coral reefs, flooding North America and chilling northern Europe, according to the study.

The study is published online in Paleoceanography, a journal of the American Geophysical Union. The lead author of the paper is University of Michigan climate scientist Ian Winkelstern, a postdoctoral researcher in the Department of Earth and Environmental Sciences.

The study is believed to be the first to record ocean temperature changes during this melting event that occurred during the last interglacial period, the time between the last two ice ages.

Large meltwater events like this one have occurred in Earth's past, but they usually happen when large continental ice sheets melt at the end of an ice age. But the new study shows melting of the Greenland ice sheet alone is enough to drive large changes in ocean circulation, according to the study's authors.

Continued melting of Greenland in the coming decades could have similar effects, such as shutting down the Gulf Stream, decimating coral reefs in Bermuda and altering the climate of northern Europe, Winkelstern said.

"If a big enough chunk of Greenland falls off, which has clearly happened in the past and has clearly caused these dramatic changes in the past, there's no reason to think it couldn't happen again," he said. "We're doing a pretty good job of melting it right now."

During the last interglacial period, Earth's climate was about as warm as it is today. Winkelstern and his team set out to study Bermuda's climate during this period to better understand what might happen as the planet warms. Bermuda is in the North Atlantic but is bathed in water from the Gulf Stream, an ocean current carrying warm water northward from the Gulf of Mexico, making it a good place to study past ocean conditions.

The researchers dug up fossilized shells of sea snails that lived during the last interglacial in two bays on Bermuda's southern coast. They used the proportion of heavy carbon and heavy oxygen in the snails' shells to calculate the temperature of the water at which the shells formed. The team compared the heavy carbon and oxygen ratios in the fossils to ratios in shells from live snails to compare water temperatures from the last interglacial to today.

In one of the bays, the researchers found the fossil shells formed in water roughly the same temperature as Bermuda's water today. But surprisingly, at the other bay, they found the fossil shells formed in water about 10 degrees Celsius (18 degrees Fahrenheit) colder and slightly less salty than today's ocean water.

The fossils from the two bays are at most only a few thousand years apart in age, meaning a large pulse of cold water must have briefly covered the North Atlantic during the last interglacial, according to Winkelstern. And the only place for that freshwater to come from during that time would be meltwater from the Greenland ice sheet, he said. The new research does not quantify how much water came from Greenland, but it was enough to disrupt ocean circulation, Winkelstern said.

While this meltwater event is not unprecedented, it hasn't been picked up in geological records like ocean cores because it was too short to be detected by these methods, Winkelstern said.

"In general, the last interglacial was warm throughout," he said. "But what we think we've captured here is this relatively brief, on the order of decades to centuries, event, where the North Atlantic was very cold and the Gulf Stream was not transporting much warm water at all."

The results show dramatic climate shifts are possible with continued warming, including large-scale changes in ocean circulation, Winkelstern said. Increased meltwater from Greenland could possibly disrupt or shut down the Atlantic Meridional Overturning Circulation, the conveyor belt transporting warm ocean water from the tropics to the North Atlantic and cold water from the North Atlantic to the equator.

"The cold conditions recorded by these shells are therefore most likely showing us what the effects of rapid melting of the Greenland ice sheet can be," Winkelstern said. "Since anthropogenic warming is currently melting the Greenland ice sheet at an accelerating pace, these results offer a potential glimpse into a future where sufficient melting has occurred to cause AMOC shutdown."

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Don't think the ice is going anywhere fast. 100 years may not give us new technology, but 1000 will - and we still have a margin of 10000 years.

But let us not stop the panic!!! Quick, freeze in the dark now.

aaaah....at it again, It seems that facts don't matter at all for this antigoracle sock, fresh out of self humiliation, he starts another attempt at idiocy, not surprisingly succeeding.....yet again :D

Nothing to see here folks, just more Pathological FAKE "science" from a desperate AGW Cult.Greenland was hotter and melting faster in the 1930s and none of this doom and gloom happened.http://www.thereg...retreat/

I couldn't help but notice that none of the AGW people took direct issue with what FactsReallyMatter wrote, rather they each immediately resorted to ad hominem attacks.

@rhugh1066let me explain it like this:the first few times you arrest a pedophile you attempt to discern his level of competence to stand trial and his ability comprehend what he did was wrong...you usually don't need to keep repeating that what they did was wrong, because they don't care. this is why recidivism is so high among most of them: they understand, but they don't care

same thing above: there have been numerous posters demonstrating the abject failure of the delusional beliefs continually regurgitated by said poster (and others, and their socks) with clear, concise science and validated studies

Nothing to see here folks, just more Pathological FAKE "science" from a desperate AGW Cult.Greenland was hotter and melting faster in the 1930s and none of this doom and gloom happened.http://www.thereg...retreat/

Still misunderstanding the facts monkey nuts ? Post spamming the same old deadbeaten links of which you have no understanding of. The warmth was mainly a regional phenomenon caused by natural factors. Compare this with the unequivocal findings of the scientific community regarding ongoing warming, climate change now is global and in all likelihood driven primarily by human activities.

Chris_Reeve

The math is quite simple, the data quite obvious. It would take in excess of 10,000 years to completely melt the greenland ice sheet, even if they went there with a blowtorch (which I heartily suggest they do).

But this is apparently still too hard for those who set aside truth for faith.

I couldn't help but notice that none of the AGW people took direct issue with what FactsReallyMatter wrote,

Because he (and you, obviously) totally missed the point of the article? Why should someone feel the need to respond to something that doesn't address any issue at all?

But fine, here you go (*sigh*). This is the the part where all the guys with neurons in the single digits should listen up. To make it clear. This means you guys:FactsReallyMatterShootistrhugh1066Chris_Reeveantigoracle

Don't think the ice is going anywhere fast.

The ice going isn't the problem. America being inundated may be. Because, you know. Ice melts = water (I know, I know, this must be a totally new fact for you. But try to keep up with modern thinking). More water in the ocean means sea level rise.Unless you think more place for fish to swim is a good idea. (Then again: for the ROW America being flooded might actually be a bonus. Carry on, then.)

Well, when as you don't understand how the ocean works perhaps you should look to the facts.....Antarctica = -4.62mm/yr (note the minus, i.e. shoreline is receding)Denmark = +1.8mm/yr UK = +.26mm/yrMidway = +1.28mm/yrWash state = -1.71mm/yr (another minus)gulf of mexcio near tex = +3.91 mm/r

FactsThatIveCherryPickedReallyMatter, all you've proven with your pitiful number of cherry-picked locations is that sea level rise is uneven. Luckily we have satellites to measure sea level everywhere, and the trend is obvious, sea level has risen rather than fallen in most areas. https://www.star...._300.png

Once again:"Yes, . . it is always the other person with the psychopathy, isn't it, otto? It matters not who the target is, the pronouncement is always the same. If you do not understand your need to continually bring this up, we must educate you.

This is a common act used by those with problems they know they have, but cannot bring themselves to admit. So they project them onto others, and make a big deal of it, hoping it will result in help for themselves.

It may be unconscious to otto, but it is transparent to the rest of us without his problems."

Chris_Reeve

...Venus is not even in thermal equilibrium. Heat in = heat out is important for the greenhouse effect, for the very reason that there is of course more than one way to heat a planet up. If heat out >>> heat in -- as was observed for Venus -- then this raises serious questions about what created the heat.

This is yet another example of complex evolving dynamical systems being treated (by BOTH 'sides') with naive/simplistic black-or-white assumptions, models etc; and so misleading everyone, on 'both sides'.

Consider timeline of planet Venus's evolution of atmospheric conditions observed now. Initially, due to closer sun proximity, the outgassing/evaporation of more types of atmospheric constituents was possible (compare that to Earth where only limited types of constituents evaporated into atmosphere). Once heat-trapping effect of Venus atmos constituents/density surpasses insolation heat inputs, then the internal heat...

...the internal heat (generated by planetary material/body formation/compression/fission/phase-changes etc) inputs a LARGER-than-solar heat-load to the surface-atmosphere climate dynamics. This is especially important if much/most of the insolation is 'stopped/reflected' back into space from the higher-altitude atmosphere layers on Venus. It would be even hotter if significant solar input still got through to lower layers! So quantification of those inputs should be refined before we can tell which is the DOMINANT input contribution on Venus (especially if Venus atmos traps ALL heat from interior!

If Earth's internal heat did not escape into space just as readily as surface/atmos SOLAR heat can, then we would have VENUS-like conditions here on Earth NOW.

No 'mysterious' or unknown sources of internal heat involved, Chris. Just the ATMOSPHERIC constituents/densities are enough to, over time, build up to Venus conditions.

Less naivete! Cheers. :)

Chris_Reeve

Feb 10, 2017

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Chris_Reeve

By whom? Yep, by naive minds based on simplistic assumptions having no regard at all to actual factors/conditions and evolutionary trajectory/outcome I just pointed out for you, complete with comparison with Earth conditions etc which differed due to atmospheric formation/density/constituents which themselves differed from Venus as I explained using known physics/inputs etc. What more do you want, Chris? Why dismiss what I have just explained, based on reasonable science/factors/comparisons etc, and opt for your own, or others', obviously (still) naive/simplistic arguments which ignore all that I have just pointed out for anyone REALLY interested in considering ALL the relevant factors involved which evolved over time due to Venus's closer Solar proximity (than Earth) in its initial 'starting' dynamics phase that evolved to diverge so greatly from Earth's NOW.

Less naivete! Cheers. :)

Chris_Reeve

Feb 10, 2017

This comment has been removed by a moderator.

Chris_Reeve

Not at all, mate. It is a 'given' by all serious researchers that the 'early' solar system was a choatic/violent system (just look at Uranus's fully tilted axis of rotation! and the early asteroid/meteorite/cometary 'bombardment' indications!). We all 'start' from that 'given' when trying to discern the various evolutionary trajectories.

That is fine as a starting point hypothesis,...

Thanks, I make it a point of science to always think things through fully instead of just going with naive regurgitated 'beliefs' (from EITHER 'side' in debates).

As for the rest of your caution re calculation/insistence beyond tenable evidence etc, yes, I agree that is an ever present trap into which many uncritical/naive/groupthink types (on all 'sides') can fall into very easily if they do not keep true to the science method principles of strict observational objectivity and personal integrity.

So a study shows that a pulse of fresh Greenland ICE melt 125,000 years ago disrupted the Atlantic Ocean circulation, killed a bunch of reefs and fish spawns, flooded North America, and caused havoc on the European weather cycles and all of the denier goon squad comes out in a fury and rage? Give it a break goons. Go watch a Jurassic (p)Ark movie and gather your views of history.

Chris_Reeve

There are many studies on topics will are much, much more likely to cause impending doom for all of mankind. Impact with asteroids comes to mind. These we could potentially do something about because we actually understand the physics involved, particularly if the funding directed to the AGW cult was instead spend on real science and technology.

There are many studies on topics will are much, much more likely to cause impending doom for all of mankind. Impact with asteroids comes to mind.

How are you calculating the relative risks? You need clarify what you mean by 'impending doom for all mankind' after all, whilst rapid climate change is bad, nobody is claiming it's going to cause the extinction of mankind, and you also need to take the relative likelihoods into account.

And why should it be all or nothing? Why can't both climate change and asteroid impact be studied as they are now?